Article containing visible temperature records and method of obtaining the records



Feb. 16,1926. 1, 73, 0 v C. T. FULLER ARTICLE CONTAINING VISIBLE TEMPERATURE RECORDS AND NETHOD 0F OBTAINING THE RECORDS Filed Jan. 26, 1922 Fig.1.

Fig.2.

Inventor: Carl T. Fuller .His ttbigey,

Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

CARL r. FULLER; oENU'rLEmNEw JERSEY, ASSIGNOR r GENERAL ELECTRIC cont- PANY, A CORPORATION or NEW YORK.

ARTICLE CONTAINING VISIBLE TEMPERATURE RECORDS AND METHOD OBTAINING THE RECORDS.

Application filed January Jersey, have invented certain new and use-- ful Improvements in Articles Containing Visible Temperature Records and Methods of Obtaining the Records, of which the following is a specification.

My invention relates to the manufacture of articles such as incandescent electric lamps and similar articles which are heated at some stage of their manufacture to :a predetermined temperature, and more par ticularly to a method of obtaining a permanent visible record of whether the article or any selected part bf it has been subjected to apredet'ermined temperature.

To obtain thebest results various kinds of articles must be heated at certain stages in their manufacture, and upon the accuracy with which they temperature depends to a large extent the quality ofthe article. This is particularly true in the case of incandescent electric lamps and similar evacuated devices, which are heated during'exhaust. When the lamp is manufactured in the usual way its quality is very greatly lowered by failure to heat all its interior parts, above a definite temperature during exhaust. Overheating also results in an inferior product. Heretofore no practical method has beeii" available to show. whether'the interior parts hadv been roperly heated, andthe productwhas thereore been variable in quality. I

One object of my invention is to provide a simple and inexpensive method by means of which it is itself whethera lamp was heated to a high enough temperature during exhaust. Another object is to provide a method of\de- .termining by mere inspection whether the lamp has been overheated 'gr underheated;

' Still another object is toproduce an incana descent lamp or similar article which contains a permanent visible record ofwh'eth'er it has been heated to a predetermined tem-" perature during its manufacture. Further objects andadvantages of my invention will hereinafter appear.

are heated to a definite,

ossible to determine 40 by mere inspection 0 the article or lamp- 26, 1922. Serial No. 532,047.

which at said temperature permanently I changes its color in a striking manner, or '60 becomes practically colorless. To show MWhether the heating of the article has been kept within a certain temperature ran e I may use two or, more indicators, one a ected. at the minimum temperature and an other at the maximum temperature It is then obvious on inspection that if both these indicators are aflected the article hasbeen overheated; if neither is affected it has been underheatedj and if one is affected and the other is not its temperature has been kept within the proper range. The coloring 'materials I, prefer to use are organic dyes which change or decompose at the selected temperatures with a marked change in appearance. Where two or more indicators are used I may mix them provided they do-not react with each other, andapply the ,mixture to the part of which the temperature is significant. Some of these dyes are water soluble, and others are soluble in elcohol, and where possible I prefer to apply them in the'form of a solution as by painting the solution on the selected part. The dyes with which I have obtained the best results' 'in lamp making are those dyes of the triphenyl methane group which undergo a permanent changeorloss of color when subjected for a suitable time interval to" temperature of 150 C. to 310 .(11 althou h a similar action occurs in some dyes of t e .diphenyl methane group, such as the dye known as auraxnine yellow, which is per- V ,manently changed at about 250- C. some other dyes, such as the 'azo dye known as spirit scarlet, may also 'be used as it dis appears at a temperature of about180 0., lt ough this dye. does not seem to break down, but to sublime at that tem erature. Since time is also a factor in the dyes. the tem erature's above given at w ichthese dyes change or fade will be correct only when the heating is comparatively I rapid as for example, when the given tjemadin of perature is attained in from two to'three minutes. If the heating is slower the dyes may fade at somewhat lower temperatures. The best mode which I at of practicing my invention in connection with incandescent lamps and similar articles may be understood by reference to the accompanying drawing, in which Figure 1 is a view of a lamp made in accordance with my invention with the indicatorap plied to certain interior parts of glass, and igure 2 shows how it may be applied tointerior parts of metal as well.

The lamp shown in Figure l is of a common type comprising a bulb 1 with a glass stem 2 from which extends a glass hub or rod 3 having buttons 4 and 5 in which are embedded the inner ends of anchors 6 on which is strung or supported the filament 7 The lead wires 8 connected to the the filament supply the current.

In accordance with my invention I obtain .a visible permanent record of whether the inner glass parts of the lamp were properly heated during exhaust by applying to thosecation of the temperature of the other parts.

If, for example, I use on the button-5 as an indicator an alcohol solution of the green triphenyl methane dye known as malachite green, which becomes practically ($010 less at about 220 0., a green button shows hat the lamp was not heated enough to raise the button to 220 0:, whilea colorless button shows that it was heated enough to raise the button above that temperature. Methyl violet, another tri-phenol methane dye which fades permanently at about 250 0., may also be used. For higher temperatures I have used\ successfully the -tri-phenyl methane dyes commercially known as Chemco red,

which changes at about 280 (1., and Chemco blue, which is not affected until a temperature of about 310 C. is reached; By' the use of these indicators I can obtain a lamp which has some part, such as the butv ton.5, or the hub 3 at the point 9, or the stem 2 at the point 10, on which there is a permanent easily visible record of'whether that particular part ever attained at that point a predetermined temperature. The advantages of this permanent record in; the lamp itself are many. -Whenever for anyreason, such as failure of gas pressure on the burners,on' faulty adjustment of the burners the lamps being made are not being heatedto'the proper temperature, that 'fact present know ends of.

becomes apparent instantly and the operator can immediately make the necessary corrections. The inspector can easily detect the lamps which were not properly heated during exhaust, and the consumer can tell by inspection whether the lamp offered him was heated as it should have been.

For some reasons it is desirable to a oid overheating as well as underheating and therefore in accordance with my invention I obtain a suitable indicator for maximum and minimum temperatures-by mixing the proper dyes selecting those which do not react chemically with each other and thereby change their characteristics under conditions of use. This mixture produces an indicator of a color different from either of its constituents. I find that when suchla inixinre is heated each constitutent acts as though the other were not present. a One dye will change and disappear at a definitetemperature, leaving the other dye as unchanged and bright as though it had been applied by itself. If, for example, a mixture of spirit scarlet and Chemco blue is applied to the button 5 and the lam is heated the scarlet disappears complete y at about 280 (3., leaving the button as vivid a blue as though the blue were thegonly dye that had been applied to it" until the button attains a temperature of about 310C. whereupon the blue disappears. In this particular case 'a 4 blue button 5 shows that the lamp was heated above 280 C. and below 310 C. In the same way a mixture of malachite green, which becomes colorless at about 220 0.,

and au'ramine yellow, which changes at about 250 C. can be used to make sure that the lamp has been heated; to between 220 C. and 250C. Similar mixtures which I have used successfully are methyl violet and Chemco blue forv temperature ranges from 250 C. and 310 'C., 'and Ohenico red and Chemco blue for temperature ranges from 280 C. to 310 C. The latter mixtureis particularly useful for lamps which should be heated quite'hot during exhaust, as a blue color of the button or other part on which the mixture is used shows'that the lamp has been heated to the proper temperature but has not been overheated.

In some type of lamps such as that shown in Figure 2, there is very little glass in the interior of the lamp, as the filament 11 is carried by the leading-in wires 12. In this .type pi lamp the temperature attained by the metal parts, such as the leads'12, is significant, and in accordance with invention the indicator may be ap led to the leads, as at the point 13 in the/same way as "applied to the glass parts of the lamp shown in Figure 1.

By my invention I obtainan article such.

which 18 novel in as an incandescent lam that 1t contains as an integral part a per-j manenteasily visible record of whether it inert to each other and-which pernfanently was heated to the proper temperature durchange color at predetermined and difierent ing manufacture. Such an 81131618 is of temperatures between 150 C. and 325C.

great value as compared with the same kind 5. An incandescent lamp or similar device 5 of articles which contain no such record. for translating electric current comprising I have obtained the best results with the a sealed envelope and having inside said endyes above described, but many other dyes velo e a temperature res onsive' material and coloring materialscanbe used in praccapafiile of permanently c anging in color ticing my invention. at a temperature higher than 150 C. 55

What I claim as new and desire to secure 6. An incandescent lamp or similar device by Letters Patent of the United States, is: comprisinga-sealed glass envelope contam- 1. The method of obtaining a permanent ing a metal filament and having on a part visible indication that, a part of an incanin the interior of the device a temperature descent lamp or similar current consuming sensitive organic dye unchanged in color at 60 device comprising a sealed glass envelope 150 C. but permanently changed in color. containin said part attained during manu-. at a higher temperature between 150 C. facture 0 the device a predetermined temand 325 C.

erature higher than said part attains dur- 7 An incandescent lam or similar demg operation of said device, which consists vice comprising a sealed g ass envelope and 65 in de ositing on said art a colored material having on an interior part inside said envelwhic permanently c anges in color when ope a coating comprising a mixture of two; said part attains said predetermined temtemperature sensitive dyes which are inert perature. p with respect to each other and both un- 2. The method which consists in applying changed in color at 150 (1., one permanently to an'interior part of an incandescent lamp changing in color at a higher temperature or similar current consuming device 'comand the other at a still higher temperature prising a sealed 'glass envelope a temperanot exceeding 325 C. ture resplonsive organic dye which perma- 8. An incandescent lam comprising a nently c an es in color when said part atsealed container, a metal lament therein, 76

tains a pre etermined temperature higher and an organic dye of the aromatic or ben- 7 than- 150 C. v zene ring series which chan es color perma- 3. The method which consists in coating nently between 150 C. an 325 C. placed an interlor part of an incandescent lamp or in said container adjacent said filament and similar current consummg device comprisexposed to the atmosphere in the bulb. 80

5 in an evacuated lass envelope with a tem- 9. An incandescent lamp comprising a perature responsive or amc dye which sealed container containing a filament and changes color permanent y when said part having adjacent said filament and exposed attains durin' the exhaust of said device a to the atmosphere in said contamer a mu:-

redetermine temperature lower than 325 ture of two organic dyes of the aromatic or I!!! C. but higher than the temperature attained benzene ring series which are chemically by said part during operation of said device. inert to each other and which change color 4. The method which consists in coating permanently at difierent temperatures withan interior part of an incande;ecent lamp or ma range of 150 C. to 325 C.

- similar device comprising a'sealed glass en- In witness whereof, I have hereunto set 4 velope containing said part with a mixture my hand this 16th dagAo January, 1922.

' o temperature responsive dyes which are L T. FULLER. 

